Lever Levers are one of the basic tools used in prehistoric times. Levers were first described ~260 BC by the ancient Greek mathematician Archimedes (287‐212 BC). Although we only learn about class 1 levers, there are actually three different types (class 2 and class 3 type levers are the others). A type 1 lever is a simple machine that involves pushing down on one side to lift the other side. The main point that holds the class 1 lever up is called the pivot. You may also hear the pivot referred to as a fulcrum. In a Type 1 lever, the pivot (fulcrum) is between the side you are pushing down and the side you are trying to lift. By moving the pivot along the length of the lever, we can change how much weight the lever can lift. Many of our basic tools and toys are type 1 levers such as scissors, pliers, and a teeter‐totter. Class 1 levers make it easier to lift things into the air. Like all simple machines, we measure how easy it is to do work with a class 1 lever based on the mechanical advantage. To calculate the mechanical advantage of a class 1 lever, you will need to … complete the lab to find out ☺ Create a graphic web for levers: Lever
How a lever works as a simple machine 1. Balance the meter stick on the fulcrum. You should see that the fulcrum needs to be centered on 50 cm. 2. Using the meter stick and fulcrum, place a 100 gram weight at the 10 cm mark. Balance a 100 gram weight somewhere on the other end of the lever. 3. Once everything is balanced, measure the distance from the pivot point out to the front edge of each weight (closest centimeter). Be approximate! It doesn’t have to be exact. Distance to the left weight Distance to the right weight 4. What do you notice about the distances on each side of the pivot point? 5. Next, place a 100 gram weight on the left side at the 10 cm mark and balance a 200 gram weight somewhere on the right side. 6. Once everything is balanced, measure the distance from the pivot point out to the front edge of each weight (closest centimeter). Be approximate! It doesn’t have to be exact. Distance to the 100 g weight Distance to the 200 g weight 7. What do you notice about the distances on each side of the pivot point? 8. How do the distances compare to the weights? 9. Next, place a 100 gram weight on the left side at the 10 cm mark and balance a 500 gram weight on the right side. 10. Once everything is balanced, measure the distance from the pivot point out to the front edge of each weight (closest centimeter). Be approximate! It doesn’t have to be exact. Distance to the 100 g weight Distance to the 500 g weight 11. What do you notice about the distances on each side of the pivot point? 12. How do the ratios of the distances compare to the ratio of the weights? 13. Create a strategy to help predict where different weights would balance on a lever. 14. Using the 50 gram weight and any weight greater than 50 grams, make a prediction for where you would place the two weights on the lever to make them balance. Weight on the left side 50 g Weight on the Predicted right side distance to 50 gram weight Predicted distance to other weight 15. Try out your prediction. Adjust as needed to balance the weights. Record the actual distance to each weight. Weight on the left side 50 g Weight on the Actual right side distance to 50 gram weight Actual distance to other weight 16. How close was your prediction to the actual distances? 17. Using the 50 gram weight and a different weight than used in step 14, make a prediction for where you would place the two weights on the lever to make them balance. Weight on the left side Weight on the right side Predicted distance to the left weight (g) Predicted distance to the right weight (g) 18. Try out your prediction. Adjust as needed to balance the weights. Record the actual distance to each weight. Weight on the left side Weight on the right side Predicted distance to the left weight (g) Predicted distance to the right weight (g) 19. How close was your prediction to the actual distances? 20. If you can only lift 100 lbs., how far from the pivot would you need to push down to lift a 500 lbs. weight located 1 m from the pivot.